SMD焊接作业(简).doc

SMD焊接作业 Keep the circuit board clean. Isopropanol or wood alcohol is suitable for removing light oils and grease. PCBs should always be washed under warm water, then oven dried at 60 degrees Celsius for 10 to 15 minutes. Handle the PCB by the edge only and avoid touching copper with your bare hands. 线路板保持干净,轻微的油渍可以使用酒精去除,冲洗PCB板务必要使用温水,然后在摄氏60度下烘干10到15分钟,过程中务必只能手触板边,绝对不能手摸铜箔,尤其是裸铜. Use the right soldering iron for the job. You dont need to purchase a temperature controlled iron, special SMT tip or SMT hot gas reflow station. These tools might be used in industry, but only to save time and increase reliability. 使用正确的烙铁,一般SMD并不需要特殊的烙铁,温控,SMD专用烙铁头,或者是热气式的焊枪,这些一般常见于工业生产用,这些工具只是可以节省时间及增加焊点可靠性,但并非是非用不可的工具. All sorts of SMT soldering jobs can be done with the common Weller workstation. The important point is select the right tip (i.e.: have several tips on hand). As with any soldering job, the general idea is to have the joint up to temperature and soldered in a few seconds. Think about how much of a heat sink the joint will be and choose the tip based on that. Use of larger tips should be limited to areas of large solid copper plane (i.e.: ground plane). For all jobs except very very small parts, I use a small tip as shown above. With practice, you will learn what tip suits you best. 一般的烙铁就可以做SMD的焊接,重点不在烙铁,而是烙铁头,进行锡焊接的要点在于接点的温度及焊接的时间,因此首先要想到的是焊接点上的吸热,并且继而想到要选用什幺样的烙铁头,一般会选用大烙铁头无非是有很大的裸铜或者是接地面上的焊点,只要有够多的经验并且注意细节,你很快就可以自己选用合适的烙铁头. Use L.M.P (Low Melting Point Solder) if you are experimenting. LMP solder is very similar to 60/40 solder, except that it contains 2% Silver. This Silver loading has two effects. It lowers the melting point (a few degrees) and it reduces the rate at which component metalisation leeches into the solder itself. 使用低融点锡,这种锡与60/40锡相同,只是另外加有2%的银,增加银有二个作用,一是降低融点,另外一个作用是增加锡融解后的延展度. SMT resistors, capacitors, ferrite beads, etc. all make there electrical connections via metalised pads deposited on a substrate (Alumina, ceramic, ferrite, etc). The metal used